Scoops and buckets for excavating machines of various kinds are commonly provided with digging teeth for the purpose of loosening the earth or other material to be excavated. Such scoops or buckets typically have a pair of side walls and a bottom wall interconnecting the side walls. Such bucket bottom wall (or "cutting edge member") provides a forwardly disposed cutting edge along which a plurality of teeth are either permanently or removably mounted.
Having removable teeth is often highly desirable because it allows use of the bucket for certain jobs which require no teeth or in which teeth are in fact a detriment. But, because of certain problems with removable teeth, the advantages of removability in many cases are intentionally given up by simply welding the digging teeth permanently onto the cutting edge member of the bucket.
Removable teeth for certain types of earth-moving buckets of the prior art frequently tend to become loosened during their use. Such loosening occurs by virtue of repetitive front and side impacts on the teeth during digging operations. Side impacts and side loads on the teeth have a particularly severe effect in causing teeth to become loosened from their attachment to the cutting edge member.
Another problem encountered with removable digging tooth assemblies of the prior art is breakage. When teeth become partially loosened in their attachment to the cutting edge member, they often move around from one side to the other during digging operations. This can lead to breakage of the shank of the tooth or in some cases breakage of one of the mounting bolts.
A digging tooth of the type removably mounted on buckets typically has a forward pointed portion and a rearward shank portion. The shank portion typically has upper and lower prongs which form a slot to receive the cutting edge member of the bucket. The slot is wider than the thickness of the cutting edge member, so that such edge member may readily be received into the slot. Many removable digging teeth of the prior art are attached to the cutting edge member by a bolting-clamping action, which allows ready attachment and removal of teeth. Due at least in part to the fact that a gap remains in the slot after the cutting edge member is inserted therein, this form of removable attachment is often inconsistent and unsatisfactory and leads to the aforementioned tooth loosening and breakage problems.
Such bolting-clamping attachment means, while allowing easy detachment and reattachment, is often unsatisfactory. While the prongs of the tooth shank can usually be well clamped to the cutting edge member near the open end of the shank slot, such attachment at points nearer to the closed end of the slot is frequently inadequate.
More specifically, the attachment means of such prior art devices near the open end of the slot is relatively secure, providing clamping contact of both prongs of the tooth shank on the cutting edge member and double shear of the mounting bolt. However, the attachment means near the closed end of the slot provides little or no clamping contact of the prongs of the tooth shank on the cutting edge member, instead leaving gaps between the prongs and the cutting edge member. Thus, the tooth can pivot back and forth about the attachment means near the closed end of the slot. This makes the tooth less effective in digging action and can lead to shank and/or connecting bolt breakage.
A number of improvements have been made in means for attachment of digging teeth to the cutting edge member of earth-moving buckets. However, there remains a substantial need for improved means for removably attaching digging teeth to the cutting edge of earth-moving buckets. It is to such need that this invention is addressed.